$FreeBSD$

--- ../zlib-1.2.3/configure.orig
+++ ../zlib-1.2.3/configure
@@ -32,7 +32,7 @@
 mandir=${mandir-'${prefix}/share/man'}
 shared_ext='.so'
 shared=0
-gcc=0
+has_cc=0
 old_cc="$CC"
 old_cflags="$CFLAGS"
 
@@ -63,17 +63,17 @@
 int hello() {return getchar();}
 EOF
 
-test -z "$CC" && echo Checking for gcc...
-cc=${CC-gcc}
+test -z "$CC" && echo Checking for cc...
+cc=${CC-cc}
 cflags=${CFLAGS-"-O3"}
 # to force the asm version use: CFLAGS="-O3 -DASMV" ./configure
 case "$cc" in
-  *gcc*) gcc=1;;
+  cc|gcc|clang) has_cc=1;;
 esac
 
-if test "$gcc" -eq 1 && ($cc -c $cflags $test.c) 2>/dev/null; then
+if test "$has_cc" -eq 1 && ($cc -c $cflags $test.c) 2>/dev/null; then
   CC="$cc"
-  SFLAGS=${CFLAGS-"-fPIC -O3"}
+  SFLAGS="$CFLAGS -fPIC -O3"
   CFLAGS="$cflags"
   case `(uname -s || echo unknown) 2>/dev/null` in
   Linux | linux | GNU | GNU/*) LDSHARED=${LDSHARED-"$cc -shared -Wl,-soname,libz.so.1"};;